Bang for the buck is great, but if you want to keep it for more than a few years go with the IBM. They are built to last.
They are more business class and will hold up to a little more banging around. The usb ports and mousepad won't break as quickly.
But if it's not too much more spring for a dell Latitude. I have had a D620 and now have a Latitude E6400 ATG. It's ruggedized and has a bullet proof display.
I've had toshiba, sony, gateway, Acer and asus in past. But after owning a dell laptop I will never buy anything else again. They are built to last.